930 LE JOURNAL OLAGBOLOGN 
Gable glacier. Just back of the point of observation there was a 
large embossment of rock, which expressed itself at the surface 
of the ice by a beautiful half dome, like the Half Dome of the 
Yosemite. The other half of the dome was cut away, revealing 
the operations at the base within Here it was observed that the 
trains of débris, apparently rubbed from the surface of the 
embossment, were being carried out almost horizontally into the 
ice in its lee. Some ofthese were short, while others extended 
several rods into the ice. They were somewhat inclined down- 
ward, but the slope of the glacier being greater, they passed out 
into the body instead of following the base of the ice. At one 
point the overthrust reached such a degree as to carry the earthy 
layers obliquely almost across the thickness of the glacier, pro- 
ducing a pronounced unconformity. (Figs 9 and 10, Pl. VIL, 
Chamberlin’) 32) 5 The mode Wor operation yseents {tom et iia. 
When the ice is forced over a prominence it settles down a little 
in its lee, and is then protected somewhat from the thrust of the 
ice behind; the next ice that passes over, being prevented by the 
former portion from settling down at once, is thrust forward over 
it. To some extent this is accomplished by the bending and 
doubling of the layers, and to some extent by distinct shearing. 
At length, however, the first layer is compelled by the general 
friction to move somewhat forward, and in time to join the com- 
mon moving mass, carrying the overthrust layer of débris 
between it and theicelayer above. The way is then open for a 
repetition of the process. This picture of the behavior of the ice 
is quite radically different from that entertained by the viscous 
hypothesis, in which the ice is supposed to flow down the lee side 
of a prominence, as if it were a liquid. The motive power here 
seems not so much gravitation pulling a fluent body forward as 
the thrust of a rigid body by a force in the rear.” 
The descriptive part of this would answer, especially inthe first 
case cited, as a perfect description of the results of Experiment 
5, Fig. 40. But the explanation cannot be accepted as apply- 
ing to the results produced in the experiments because they were 
obtained in warm wax, a viscous body, incapable of shear along 
